Edge guidance mechanism for flexible sheet material

ABSTRACT

A SEWING MACHINE BED, FOR INSTANCE, IS PROVIDED, AHEAD OF ITS STITCH FORMING MECHANISM, WITH AN EDGE GAGE AND MEANS ACTING NORMAL TO THE DIRECTION OF FEED OF A FEED DOG AND PRESSER FOOT FOR URGING THE MARGIN OF A WORKPIECE YIELDING AGAINST THE EDGE GAGE, WHEREBY THE WORKPIECE RECEIVES A STEAM PARALLEL TO ITS MARGINAL EDGE EVEN IF THE LATTER IS CURVILINEAR.

Nov. 2, 1971 R. w. GRAY ETAL 3,616,771

EDGE GUIDANCE MECHANISM FOR FLEXIBLE SHEET MATERIAL Filed March 15, 1970In venforo Ric/20rd 14/ Gray Paula? Morgan Pa a! G Eumbal) By theirAftomey United States Patent Ofiice 3,616,771 Patented Nov. 2., 19713,616,771 EDGE GUIDANCE MECHANISM FOR FLEXIBLE SHEET MATERIAL Richard W.Gray, Marblehead, Paul E. Morgan, Melrose, and Paul G. Rumball, Beverly,Mass., assignors to USM Corporation, Boston, Mass.

Filed Mar. 13, 1970, Ser. No. 19,257 Int. Cl. D]: 35/10 U.S. Cl. 112-1532 Claims ABSTRACT OF THE DISCLOSURE A sewing machine bed, for instance,is provided, ahead of its stitch forming mechanism, with an edge gageand means acting normal to the direction of feed of a feed dog andpresser foot for urging the margin of a workpiece yieldingly against theedge gage, whereby the workpiece receives a seam parallel to itsmarginal edge even if the latter is curvilinear.

CROSS REFERENCE FOR RELATED APPLICATION An application Ser. No. 9,185was filed Feb. 6, 1970 in the name of Paul Morgan and relates to an airflow work orienting mechanism.

BACKGROUND OF THE INVENTION Manufacture of apparel and other articlesoften requires that a seam be sewn parallel to an edge. Particularlywhen a workpiece is flimsy and of irregular Shape the operation becomesburdensome since practically constant manual guidance is ordinarilyrequired. Several prior approaches have been proposed for automaticallyguiding a workpiece relative to an intermittently operative tool such asa needle. Most of these, such as that disclosed in United States LettersPatent No. 3,080,836, issued Mar. 12, 1963 in the names of John E.Clemens et al., disclose somewhat complex mechanism whereby a steeringtorque is exerted in accordance with curvature of the work edge assensed in the operating locality of the tool. While such guidancemechanisms are generally useful and reliable, it is desirable to providea simpler guidance arrangement in many cases even though some sacrificeof precision be entailed.

SUMMARY OF THE INVENTION A main object is to provide an improved, simplework guidance means operable continuously and yieldingly on a workpiece.It is another and more specific object of this invention to provide in amachine, for instance a sewing machine having feed mechanism operativein the intervals when a workpiece is disengaged from a tool such as aneedle, a simplified guidance device for automatically determining theoperating path of the tool substantially parallel to an edge of thework.

To this end in one illustrative embodiment a feature of the inventionresides in providing in combination with a sewing machine having aneedle, presser foot, and cooperative feed dog, a continuously operativedevice for yieldingly urging a workpiece in its own plane normal toBRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features ofthe invention will now be more particularly described in connection withpreferred embodiments and with reference to accompanying drawingsthereof, in which:

FIG. 1 is a perspective of a portion of a sewing machine having aworkpiece on its bed, and provided with a pneumatic edge guidance devicecooperating with stitch forming and feeding mechanisms;

FIG. 2 is a plan view of the operating instrumentalities shown in FIG.1;

FIG. 3 is a view in elevation, looking along the line of feed and towardthe presser foot shown in FIGS. 1 and 2, and

FIG. 4 is a view corresponding largely to FIG. 1 and illustrating analternate construction when a light friction means is substituted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. l-3inclusive, a fiat bed 10 of a largely conventional sewing machine isformed with an opening for enabling a feed dog 12 to cooperate inorbital manner with the underside of a presser foot 14. For a purposesubsequently indicated, the presser foot 14 includes a depending spacerportion 15 extending beneath the underside of the presser foot at alocality where the spacer will not engage a workpiece W. The workpiece Wis inserted edgewise between the presser foot and feed dog to be fedfrom right to left along a straight line F (FIG. 2) in increments. Avertically reciprocable needle 16 is operable in a slot 18 of thepresser foot in usual manner. It will be understood that the presserfoot may be lifted to an out of the way position when desired and isspringpressed downwardly. In FIG. 1 dash lines at 20 indicate an upperposition to which the presser foot 14 may be urged by the feed dog 12 inthe course of Work feeding.

Guidance mechanism to be described comprises an edge gage 22 in the formof a vertical pin. It is supported by an angular arm 24 secured to thebed by screws 26 and preferably extends freely through an aperture 27 inthe presser foot. In the construction shown in FIGS. l3, the edgeguidance means also includes an air flow device having an inlet 28 inthe bed, a deflector 30 thereon for receiving air from the inlet anddirecting it in a stream parallel to the bed, beneath the workpiece,ahead of the needle, and toward the edge gage 22. The continuous streamof air thus flows generally normal to the line F of mechanical workfeeding and is effective, when the work is not clamped by the presserfoot and feed dog, to urge the work counter-clockwise (as seen in FIGS.1 and 2) about the axis of the needle 16 while it is penetrating thework. The spacer portion 15 on contacting the bed 10 insures that whenthe presser foot is in lowermost position, the feed dog having retracteddownwardly, the air stream will not be blocked by the presser foot butcan elfect steering of the work about the needle. Such pivotal movementof the work in the operating zone is limited by edge engagement of thework with the gage 22, any relative sliding movement of the work withrespect to the bed 10 being facilitated by the air bearing effectprovided by the continuous air stream.

It will be appreciated from the foregoing that during each interval ofwork steering by means of the air flowing along the underside of thework, no actual turning moment will be effected when the work edgeextends parallel to the straight line of feed F imparted by the presserfoot 14 and feed dog 12. However, when a portion (such as those marked34 in FIG. 2) of the edge of the work progressively contacting the gage22 deviates outwardly with respect to the straight line of feed F, thereis an accommodating reactionary force applied by the gage to the workmargin thereby properly turning the work clockwise as viewed in FIG. 2about the axis of the needle. When other marginal portions such as thoseindicated at 32 in FIG. 2 deviate inwardly with respect to the line F,they are progressively kept in yielding contact with the gage 22 byreason of the air stream turning the operating locality of the workpiece counterclockwise about the needle axis. It will be understoodthat, though not herein shown, a valve may be provided for adjusting thevolume and/or speed of the air flow into the inlet 28, greater flow andspeed usually being required for heavier fabrics, for instance, and lessbeing needed for flimsier materials.

In FIG. 4 a construction similar to that above described is shown exceptthat in lieu of an air stream being applied for working steering, alight friction means generally designated 36 is applied as nextexplained. As herein illustrated a slot 38 is provided in the presserfoot 14 in a locality above the feed dog 12 and between the needle 16and the gage 22. In this slot is disposed an elongated, inclinedconveyor track 40 for rotatably supporting an endless friction belt 42.As indicated in FIG. 4 the belt 42 preferably includes a backing strip44 and a work engaging fibrous material 46. This material is usuallycharacterized by being soft and fluffy thereby enabling its free fibreends to apply only a light frictional force for wiping and yieldablyurging the work normal to its line of feed and against the edge gage 22.As shown the fibrous material has light frictional contact over a shortwork locality 48 wherein it is guided by the track 40 parallel to thework surface and approximately up to the work edge. The width of thebelt 42, measured transversely thereof and along the direction ofmechanical work feed, is preferably quite narrow (on the order ofone-tenth of an inch) to avoid interference with presser foot and feeddog cooperation.

The arrangement shown in FIG. 4 operates essentially in the same manneras above described with reference to FIGS. 1-3, the light frictionalwork-steering force being continuously operative as the belt 42 isdriven by means of a rotary wheel 50 journaled in the upper end of thetrack 40 and engageable with the backing strip 44. The belt tends toapply steering influence counterclockwise about the needle 16 when it isdown and able to serve as a pivot. There is a tendency to clockwiserotation of the work at other times about the needle as pivot,overcoming influence of the belt, due to reaction force exerted by theedge gage. Accordingly, for a straight edged portion of the work thereis a net tendency due to the belt 42 to maintain edge contact with thegage 22 without disturbing 4 straight line feed. Deviation in marginalcurvature enables the belt 42 and the gage to compensate approximatelyfor such curvature whereby the seam generally follows the curved workedge. In general it is found that the presser foot 14 in thisarrangement may be made less yieldable upwardly during operation than inthe case of the alternate structure of FIGS. l3, thereby insuring thatno undue frictional interference with the belt is caused by operation ofthe feed dog. When preferred, of course, the friction means 36 as awhole may be mounted to yield heightwise.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

1. The combination with a sewing machine having a bed for slidablysupporting a workpiece having a straight and/or curvilinear edge, stitchforming mechanism including a reciprocable needle, and work feedingmechanism operative rectilinearly to advance the work on the bed whenthe needle is disengaged from the work, of a work guidance devicecomprised of an edge gage ahead of the needle and having a roundedsurface for point contact with the work edge, and guidance mechanismoperative ahead of the needle and generally normal to the direction ofsaid rectilinear advance to urge an edge of the work yieldingly againstthe edge gage, said guidance mechanism including an inlet for directingair parallel to the bed and along the underside of the work and beingeffective pivotally on the work about the needle when it engages thework.

2. The combination as set forth in claim 1 wherein the work feedingmechanism includes a vertically reciprocable presser foot and a feed dogarranged in intermittently cooperative relation, the presser foot beingyieldably mounted and having a spacer portion remote from the gage andarranged to abut the bed whereby the foot avoids blocking the air flowfrom said inlet to the gage.

References Cited UNITED STATES PATENTS 3,496,891 2/1970 KOSrOW et a1.ll2153 X 3,204,591 9/1965 Pickett ll2Dig. 2 2,573,170 10/1951 Wiegandt112-151 3,204,590 9/1965 Rockerath et al. 112203 X 3,099,970 8/1963 Hite112Dig. 2 2,630,772 3/1953 Ederer ll2136 X H. HAMPTON HUNTER, PrimaryExaminer

